Variation of straylight between contra lateral eyes - results from 1017 healthy subjects

New Terminology and Methodology for the Assessment of the Vitreous, Its Floaters and Opacities, and Their Effect on Vision: Standardized and Kinetic Anatomical and Functional Testing of Vitreous Floaters and Opacities (SK VFO Test)

OBJECTIVE

To introduce VFO and SK VFO Test: new, more representative terminology for symptoms of vitreous floaters/opacities (VFO) and new standardized kinetic (SK) anatomical-functional assessment.

MATERIALS AND METHODS

Eight eyes underwent before-after limited vitrectomy (LV): best-corrected visual acuity, low-luminance visual acuity, Minnesota Low Vision Reading Chart near visual acuity in logMAR, contrast sensitivity function (CV1000E), and straylight measurements (SM) (HDA/LDA/C-Quant). SK infrared confocal scanning laser ophthalmoscopy (SK IRcSLO) and swept-source widefield optical coherence tomography (SS-WF-OCT) identified VFO and posterior vitreous detachment (PVD). SK IRcSLO was performed with gaze directed towards the extreme superior, inferior, and lateral directions.

RESULTS

Anatomical-functional results after LV improved in 7 eyes (87.5%): objective scatter index (27.34%), disturbance index (47.97%) and C-Quant Log units (2.26%). Pre-LV SK IRcSLO and SS-WFOCT imaging identified dynamic well-defined VFO and PVD status (100%). A residual asymptomatic anterior cortical vitreous-induced shadowing ripple effect was detected post-LV.

CONCLUSIONS

This is the first objective-standardized test accounting for VFO kinesis and intermittent effect. There is potential for personalizing treatment and establishing best candidates for laser or surgery. [Ophthalmic Surg Lasers Imaging Retina 2023;54:306-315.].

Straylight As The Result Of Refractive Correction

Purpose

To investigate the effect of refractive correction on straylight.

Patients and methods

Straylight values were measured with the C-Quant (Oculus Optikgeräte, GmbH, Wetzlar, Germany) in 1) near-emmetropic eyes (n=30) with various negative powered refractive lenses and in 2) myopic eyes (n=30) corrected with prescribed eyeglasses and contact lenses. The straylight measurements in each group were compared in the different conditions.

Results

In the near-emmetropic group, a significant effect (p<0.001) of each added negative diopter was found to increase straylight values with 0.006 log-units. In the second group, no significant correlation with type of correcting lens was found on straylight values.

Conclusion

Refractive correction with high minus power (contact) lenses result in subtle increase of straylight values. These changes are relatively small and do not lead to visual disability in a clinical setting.

The significance of changes in pupil size during straylight measurement and with varying environmental illuminance

PURPOSE

In this work, we investigated the pupillary conditions during straylight measurement, and the potential effect this might have on the measured straylight.

METHODS

Five young (26-29-years-old) and 15 older (50-68-years-old) individuals participated in this study. First, the pupil diameter of both eyes was measured at three room illuminances. Next, straylight was assessed at two room illuminances. Simultaneously, the change in pupil size of the fellow eye was registered by a camera.

RESULTS

Pupil size decreased with room illuminance and with age (both p<0.05). The dependency of pupil size on age decreased as room illuminance increased (0.018mm/year at 4 lux, 0.014mm/year at 40 lux, and 0.008mm/year at 400 lux illuminances). However, during straylight measurement, pupil sizes hardly differed between 4 and 40 lux illuminances. Respective pupil sizes corresponded with 399 and 451 lux adaptation on average. No statistically significant difference was found between the straylight under the two illuminances with average R2=0.85, p<0.05.

CONCLUSION

We conclude that the illuminance of the examination room during straylight assessment does not affect the outcome in normal eyes. In fact, under mesopic and scotopic conditions, the luminance of the test field is so much higher than that of the room so that it determines the pupil size. Regardless of the lighting level, straylight measured in a laboratory, is valid for photopic pupils at an adaptation level corresponding with about 400 lux room illuminance.

Clinical features and visual function in a patient with Fish-eye disease: Quantitative measurements and optical coherence tomography

Purpose

We describe a case of fish-eye disease (FED) where the clinical features and visual function were investigated using anterior segment optical coherence tomography (OCT) and quantitative measurements.

Observations

A 36-year-old Japanese woman with FED presented with bilateral corneal opacities and visual complaints. Both contrast sensitivity and straylight were measured and OCT imaging was performed. Contrast sensitivity and straylight measurements revealed remarkably decreased visual function, despite good visual acuity. OCT demonstrated homogenously hyper-reflective corneal opacification, and a normal total corneal thickness.

Conclusions and Importance

The findings from this case suggest that OCT is useful for analyzing the clinical features of FED, and that the quantitative measurement of visual function furthers the understanding of vision-related symptoms in FED, despite good visual acuity.

Ocular Straylight with Different Multifocal Contact Lenses

PURPOSE

Multifocal contact lenses have been growing in popularity as a modality to correct presbyopic eyes, although visual side effects such as disability glare have been reported. The objective of this study was to investigate the effect of multifocal contact lenses on disability glare by means of ocular straylight.

METHODS

A prospective randomized, comparative study was performed that included 16 subjects free of ocular pathology. Straylight was measured using a commercial straylight meter with the natural and dilated pupil. Participants were fitted with Proclear Multifocal (Distance/Near), ACUVUE Oasys for Presbyopia, and Air Optix Aqua Multifocal randomized to the left or right eye. Straylight measurements were repeated with the contact lens in situ after the pupil dilation. Results obtained with the dilated pupil without contact lens acted as a control.

RESULTS

Diameter of the natural and dilated pupil was 2.87 ± 0.40 mm and 7.45 ± 0.86 mm, respectively (P < .001). After pupil dilation, straylight increased from 0.92 ± 0.13 log(s) to 1.04 ± 0.11 log(s) (P < .001). Of the four studied lenses, a significant difference was only found between Air Optix and the control group (P = .006). The latter showed also slightly increased light scatter.

CONCLUSIONS

A difference in measured straylight was found between the studied multifocal lenses. The observed variability and the straylight-pupil size dependency should be taken into account to avoid elevated straylight in multifocal contact lens wearers. The reason for the observed differences in straylight must be the subject of future studies.

Effect of vitreous opacities on straylight measurements

PURPOSE

To evaluate the effect of vitreous floaters on intraocular straylight.

METHODS

Records of bilaterally phakic patients with unilateral complaint of floaters as the main symptom were identified from an electronic database. Patients who underwent straylight measurements on both affected and unaffected eyes using a C-Quant straylight meter were selected. Data were collected on age, sex, visual acuity, straylight measurements, and optical coherence tomography. The unaffected eye served as a control.

RESULTS

Fifteen cases were included (7 women and 8 men; mean age, 54.3 years; age range, 24-71 years). Visual acuity was not correlated with the complaint of floaters. Average straylight value in eyes with floaters was 1.426 log(s) (±0.23 SD) with a median value of 1.52 log(s). The mean value for fellow eyes was 1.275 (±0.23 SD) with a median of 1.25 log(s). The differences between both groups using a Wilcoxon matched-pair signed-rank test was statistically significant at P = 0.0009. On optical coherence tomography, most patients had a confirmed or probable posterior vitreous detachment. However, in four patients, a posterior vitreous detachment was absent in the affected eyes. Vitreous floaters were inconsistently imaged by optical coherence tomography, with only a few patients presenting appreciable condensations close to the retinal surface. These were present in both affected and unaffected eyes.

CONCLUSION

Intraocular straylight is significantly increased in eyes affected by floaters. No correlation was seen with vision or optical coherence tomography appearance. Straylight is an independent objective measure of visual perception that seems to be closely correlated to complaints expressed by patients experiencing floaters.

History of ocular straylight measurement: A review

The earliest studies on 'disability glare' date from the early 20(th) century. The condition was defined as the negative effect on visual function of a bright light located at some distance in the visual field. It was found that for larger angles (>1 degree) the functional effect corresponded precisely to the effect of a light with a luminosity equal to that of the light that is perceived spreading around such a bright source. This perceived spreading of light was called straylight and by international standard disability glare was defined as identical to straylight. The phenomenon was recognized in the ophthalmological community as an important aspect of the quality of vision and attempts were made to design instruments to measure it. This must not be confused with instruments that assess light spreading over small distances (<1 degree), as originating from (higher order) aberrations and defocus. In recent years a new instrument has gained acceptance (C-Quant) for objective and controllable assessment of straylight in the clinical setting. This overview provides a sketch of the historical development of straylight measurement, as well as the results of studies on the origins of straylight (or disability glare) in the normal eye, and on findings on cataract (surgery) and corneal conditions.